Macrolides are multi-membered lactone rings having one or more deoxy sugars as substituents. Erythromycin, azithromycin, and clarithromycin are macrolides that have bacteriostatic and/or bactericidal activity.
Tacrolimus (FK 506) is also a macrolide antibiotic that is also an immunosuppressive agent. More potent than cyclosporin, tacrolimus has a selective inhibitory effect on T-lymphocytes.
The macrolides are typically obtained by fermentation, although synthetic routes to some are known. The present extraction method offers several advantages over the prior art. For example, the entire fermentation broth can be used as starting material for the present method (“whole broth method”) and the use of hydrophobic extraction solvent results in an efficient extraction yield, leaving behind most water-soluble impurities, with removal of mycelium in one step. Concentration under reduced pressure at temperature above 25° C. and reduced pressure results in a high evaporation rate of solvent without precipitation or decomposition of tacrolimus. Further advantages of the present invention will be apparent to the skilled artisan.